Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!SPARTA.COM!steveg From: steveg@SPARTA.COM (Steve Goldstein) Newsgroups: comp.sys.atari.st Subject: 1040ST memory upgrades Message-ID: <8903272114.AA05051@sparta.com> Date: 27 Mar 89 21:14:32 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 28 As far as I know, you have to go from 1MB to 2.5MB all in one shot. The way I understand it, is the MMU (memory management unit) in the ST has main memory organized into two banks, each which can be configured to use different size chips. The 1040's have two banks of 256k chips, each bank has 16 chips (16 bits or 2 bytes per word). 16*256K*1bit = 512K BYTES per bank. When you upgrade, you are reconfiguring one bank of memory to use 1MBit parts, thus the upgraded bank has 16*1024K*1bit = 2048K BYTES or 2MB, plus the 1/2 meg in the other bank = 2.5 megs. Note that this process leaves you with 16 256k x 1 chips, which you may or may not be able to sell (maybe to a 520 owner looking to upgrade to 1 meg...). The next step of course is to replace the other bank of 256k chips, with 1Mbit parts for a total of 4meg. Unfortunately, to my knowledge, the current MMU cannot handle 4Mbit chips, so the possibility of a 16 meg ST is out... -------------------------------------------------------------------------- Disclaimer (since they seem to be so popular): The above information is correct to the best of my knowledge, however I cannot be responsible for anything resulting from the use of this information. I will admit that any errors above are my own, and would appreciate corrections if there is a need for them. -- Steve Goldstein